d and then exhaling only when his lungs felt as if they would burst.
He could see Regulus overhead, and Sirius, the two great stars shining
brilliantly in the absolute blackness of space. He raised himself slowly
on one elbow and looked at the oxygen indicator. He saw that the needle
had dropped past the empty mark. He knew it wouldn't be long now. And he
knew what he had to do. He took a last long look at the two giant stars,
and then closed his eyes.

Tom no longer tried to control his breathing, but took deep satisfying
lungfuls of oxygen and in a few moments slipped into a sound sleep.

The jet boat roared on, carrying its sleeping occupant in an endless
spiral around the nameless asteroid.

Not too many miles away, alone on the radar bridge of the giant rocket
cruiser, Roger Manning, sweat popping out on his forehead, was trying
the radar scanner on the three-hundred-and-tenth point on the compass.
He connected the wires, glanced at the scanner, and shook his head
disgustedly. The scanner screen was still dark. Having adjusted the
delicate mechanism to eliminate the white flashes of static, he couldn't
find them again. He sat back in his chair for a moment, mopping his brow
and watching the white hairline in its continuous swing around the face
of the scope. As the line swept to the top of the screen, he saw the
blip outline of a jet boat and recognized it as one belonging to the
_Polaris_. Then, slowly, the line swept down and Roger suddenly saw the
blip outline of a second craft. With the experienced eye of a radar
veteran, Roger was able not only to distinguish the jet boats from the
asteroids, but from each other. He gripped the edge of the instrument
and shouted at the top of his voice. The second boat was a different
model!

He reached for the audioceiver and switched it on.

"Attention! Attention! Captain Strong! Astro! Come in! This is Manning
aboard the _Polaris_! Come in!"

Strong and Astro replied almost together.

"Strong here!"

"Astro here!"

"I've spotted a jet boat!" Roger shouted. "You think it might be--"

"Where?" bawled Astro before Roger could finish. "Where is it, you
rockethead?"

"As close as I can figure it, he's circling an asteroid, a big one, at
the intersection of sections twenty-one and twenty-two!"

"Twenty-one and twenty-two! Got it!" yelled Astro.

"I'll meet you there, Astro!" said Strong.

Astro and Strong turned their small ships in the direction of the
intersec